Fix long lines in lastStart.txt not outputting in log outputs

[spowelljr]

Problem

bufio.NewScanner has a max token length of 64KB link, sudo runc list -f json was sometimes generating an output greater than 64KB, causing the following error when running minikube logs:

failed to output last start logs: failed to read file /home/jenkins/minikube-integration/19736-7672/.minikube/logs/lastStart.txt: bufio.Scanner: token too long

Changed to bufio.NewReader to handle reading the lastStart.txt file as there is no max token size.

Thanks to @prezha for helping debug!

[medyagh]

/ok-to-test

[minikube-pr-bot]

kvm2 driver with docker runtime

+----------------+----------+---------------------+
|    COMMAND     | MINIKUBE | MINIKUBE (PR 19740) |
+----------------+----------+---------------------+
| minikube start | 48.1s    | 48.7s               |
| enable ingress | 15.2s    | 15.9s               |
+----------------+----------+---------------------+

Times for minikube start: 51.3s 46.0s 45.6s 49.6s 48.1s
Times for minikube (PR 19740) start: 51.7s 45.6s 46.2s 50.3s 49.5s

Times for minikube ingress: 14.5s 16.0s 15.0s 15.5s 15.0s
Times for minikube (PR 19740) ingress: 15.4s 15.0s 15.0s 14.5s 19.5s

docker driver with docker runtime

+----------------+----------+---------------------+
|    COMMAND     | MINIKUBE | MINIKUBE (PR 19740) |
+----------------+----------+---------------------+
| minikube start | 22.8s    | 23.0s               |
| enable ingress | 13.1s    | 12.7s               |
+----------------+----------+---------------------+

Times for minikube ingress: 13.3s 12.8s 13.3s 12.8s 13.3s
Times for minikube (PR 19740) ingress: 13.3s 12.3s 12.8s 11.3s 13.8s

Times for minikube start: 24.4s 24.7s 21.1s 22.0s 21.9s
Times for minikube (PR 19740) start: 23.4s 24.7s 23.4s 22.1s 21.4s

docker driver with containerd runtime

+----------------+----------+---------------------+
|    COMMAND     | MINIKUBE | MINIKUBE (PR 19740) |
+----------------+----------+---------------------+
| minikube start | 21.6s    | 21.9s               |
| enable ingress | 26.2s    | 30.2s               |
+----------------+----------+---------------------+

Times for minikube (PR 19740) start: 22.8s 22.2s 22.7s 20.6s 21.0s
Times for minikube start: 22.7s 19.5s 19.6s 23.8s 22.6s

Times for minikube ingress: 22.8s 23.8s 22.8s 38.8s 22.8s
Times for minikube (PR 19740) ingress: 22.8s 39.3s 38.8s 26.8s 23.3s

[minikube-pr-bot]

Here are the number of top 10 failed tests in each environments with lowest flake rate.

Environment	Test Name	Flake Rate
KVM_Linux (1 failed)	TestNoKubernetes/serial/StartNoArgs(gopogh)	2.40% (chart)

Besides the following environments also have failed tests:

• KVM_Linux_crio: 34 failed (gopogh)

• QEMU_macOS: 100 failed (gopogh)

• Docker_Linux_containerd_arm64: 2 failed (gopogh)

• Docker_Linux_crio: 2 failed (gopogh)

• Docker_Linux_crio_arm64: 2 failed (gopogh)

To see the flake rates of all tests by environment, click here.

[medyagh]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: medyagh, spowelljr

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[medyagh]

I did not find "bufio.Scanner: token too long" in the kvm linux crio, which is good ! thank you both @prezha and @spowelljr